The proposed research will involve study of Nerve Growth Factor (NGF) content in the brain, and a number of body organs of the mouse and rat at several different ages during the perinatal period of development. Our hypothesis is that there are age-related developmental relationships of NGF in these organs as well as in amniotic fluid and placenta, which when related to known biochemical and physiological parameters of development, will provide insight into the metabolic control and regulation of early nervous system development. Thus, we have established a radioimmunoassay for mouse NGF in tissues, and are in radioreceptor assay for NGF. We have purified mouse NGF from submaxillary gland, rat NGF from placenta, and human NGF from placenta. We will continue to study these normal biochemical interrelationships and will also study these hormonal and biochemical relationships under conditions of hyper- and hypothyroidism as well as hyperglucocorticoidism and undernutrition.